[9fans] Venti config for booting from fs(3) - Plan9

This is a discussion on [9fans] Venti config for booting from fs(3) - Plan9 ; I'd like to set up my spiffy new cpu server to boot from a venti
using at least mirrored arenas via fs(3). A few questions on this:
• I'm mirroring the arenas to insure against drive failure. Does it
make ...

[9fans] Venti config for booting from fs(3)

I'd like to set up my spiffy new cpu server to boot from a venti
using at least mirrored arenas via fs(3). A few questions on this:
• I'm mirroring the arenas to insure against drive failure. Does it
make sense to also interleave the indexes? Both of them?
• I've got three disks. The venti arenas will be on two. Will the
indexes benefit significantly from either being interleaved across
three, or only on the third (with the fossil)? I understand that this
is somewhat usage-dependent; I guess the real question is how
sensitive are the indexes to write times?
• The venti would be used for the fossil boot partition, so needs to
be there at startup. fs(3) suggests sticking the config on a floppy
(!). This seems like not the most reliable option. Where are others
sticking their fs(3) configs for boot?
• Once there's an fsconfig var, how does the rest of the startup go?
I don't see it pulling that in anywhere. This needs to be well before
cpurc, right? Will this require a custom boot?
Anthony

Re: [9fans] Venti config for booting from fs(3)

since modern disks can read a whole track at once, there's no "reload"
time. it would only make sense to interleave you have more than 1 i/o
process (venti seems to have a few) and you're either running faster
than the disk bandwidth. the disk bandwidth could be as high as 60MB/s
for sequential reads and as low as 1MB/s for small reads with many seeks.

if most of venti's io is via the read ahead process, i think there would
be very limited benefit by interleaving i/o. and you would need four
disks. if you use two disks partitioned in Â½, you will insure that every
write will generate a huge seek.